* Which 5-GHz channels does your 802.11a vendor support?
If you want as many wireless LAN channels as possible at your disposal to avoid co-channel interference, ask the vendors you are evaluating precisely which 5-GHz bands they support in their 802.11a access points and network interface cards.
This is advisable because North American regulations surrounding the 5-GHz band for 802.11a are changing. Within the year (or thereabouts), the FCC will allow an extra 11 channels and 255 MHz of spectrum in the “middle band” of the frequency, from 5.470 GHz to 5.725 GHz.
So going forward, you might consider purchasing notebook computers with universal WLAN NICs – those that support not only 802.11a, b, and g, but also, within 802.11a, support for the lower, middle, and upper 5-GHz bands. This is important because, increasingly, notebook computers will be shipping with WLAN NICs embedded as mini-PCI cards or other internal form factors that won’t be simple to change out.
If the NICs you purchase now in your laptops don’t support the middle band, they won’t work in those extra channels in your APs or in hot spots or on guest networks at other organizations. So it would be helpful if your vendor could provide a software driver enabling you to simply “turn on” support for the middle band, rather than requiring you to replace user laptops to do so when that band goes live in North America.
With the addition of the 5-GHz middle band, you could soon have 27 wireless channels at your disposal:
* 2.400 – 2.483 GHz – 3 channels (802.11b/g combined have 3 non-overlapping channels between them).
* 5.15 – 5.35 GHz – 8 channels (lower band for 802.11a).
* 5.470-5.725 GHz – 11 channels (the “new” middle band for 802.11a).
* 5.725-5.850 GHz – 5 channels (upper band for 802.11a).
Bottom line: If a product is labeled “802.11a-certified” by the Wi-Fi Alliance, that doesn’t guarantee support for all the 5-GHz bands. So not all 802.11a products are created equal.
